<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>CSS选择器-后代选择器</title>
    <style>
        div{
            width: 200px;
            height: 100px;
            /*1px 代表边框的厚度*/
            border: 1px solid red;
            margin-top: 5px;
        }
        .d1 div,.d2 div{
            width: 194px;
            height: 94px;
            margin: 2px;
        }
        .d2 div{
            border-color: green;
        }
    </style>
</head>
<body>
<!--后代选择器不等于儿子选择器-->
<div class="d1">
    <div></div>
</div>
<!--要求D2下的Div边框线颜色为绿色-->
<div class="d2">
    <div></div>
</div>
</body>
</html>